Thermodynamics of decoherence

TL;DR

This paper explores the thermodynamics of pure decoherence, revealing that even without energy exchange, decoherence causes nontrivial heat dissipation obeying fluctuation relations, with implications demonstrated in cold atom experiments.

Contribution

It introduces a detailed thermodynamic analysis of pure decoherence, showing how heat is generated and characterized without energy exchange, and connects theory with cold atom experiments.

Findings

Decoherence induces nontrivial heat dissipation obeying fluctuation relations.

Heat distribution differs from work distribution, resembling a mixture of cyclical process distributions.

Experimental demonstration with a qubit in a degenerate Fermi gas confirms theoretical predictions.

Abstract

We investigate the nonequilibrium thermodynamics of pure decoherence. In a pure decoherence process, the system Hamiltonian is a constant of motion and there is no direct energy exchange between the system and its surroundings. Nevertheless, the environment's energy is not generally conserved and in this work we show that this leads to nontrivial heat dissipation as a result of decoherence alone. This heat has some very distinctive properties: it obeys an integral fluctuation relation and can be interpreted in terms of the entropy production associated with populations in the energy eigenbasis of the initial state. We show that the heat distribution for a pure decoherence process is different from the distribution of work done by the initial system-bath interaction quench. Instead, it corresponds to a mixture of work distributions of cyclical processes, each conditioned on a state of the open system. Inspired by recent experiments on impurities in ultra-cold gases, we demonstrate our general results by studying the heat generated by the decoherence of a qubit immersed within a degenerate Fermi gas in the lowest band of a species-selective optical lattice.